Chapter 9 Stress and Adaptation Essentials of Pathophysiology Chapter 9 Stress and Adaptation

PRE LECTURE QUIZ (True/false) The sympathetic nervous system manifestation of the stress reaction has been called the fight-or-flight response. According to Walter B. Cannon, allostasis is achieved through a system of carefully coordinated physiologic processes that oppose change, not the ability to achieve stability through change. The alarm stage is the third stage of the general adaptation syndrome (GAS). The stress response is strongly influenced by both the nervous and the endocrine systems. Nutrition, physiologic reserve, psychosocial factors, and sleep–wake cycles are known to affect a person’s appraisal of a stressor and the coping mechanisms used to adapt to the new situation.

PRE LECTURE QUIZ With regard to post-traumatic stress disorder (PTSD), the ______________ state refers to the reexperiencing of an event through the occurrence of “flashbacks” during waking hours or nightmares in which the past traumatic event is relived. According to Hans Selye, the events or environmental agents responsible for initiating the stress response are called _________________. There are a number of ________________ that are released from the hypothalamus, anterior pituitary, and adrenal cortex in response to stress. __________________ describes a personality characteristic that includes having a purpose in life and the ability to conceptualize stressors as a challenge, rather than a threat. The ability of body systems to increase their function given the need to adapt is known as _________________ reserve. Hardiness Hormones Intrusion Physiologic Stressors

Homeostasis The body requires that a level of homeostasis or constancy be maintained during changes in internal and external environments. Give an example in which your body kept some aspect of its internal environment stable. Aspects you might consider include: Water balance Weight Blood glucose Temperature

Allostasis A difference between the perceived situation and desired situation causes the person to take action Cognitive activation theory of stress

General Adaptation Syndrome (GAS) Also called generalized stress response Corticotropin-releasing hormone (CRH) production Antidiuretic hormone release Sympathetic nervous system (SNS) activation Renin-angiotensin-aldosterone pathway activation

stressors signs and change the internal symptoms environment of part of of the the body change general adaptation signs and response helps maintain symptoms of the normal function in spite general adaptation of the stressor response

Cortisol — The “Stress Hormone” Hypothalamus CRH Helps regulate the stress response Diverts metabolism from building tissues to supplying energy for dealing with the stress Causes signs and symptoms of chronic stress Anterior pituitary ACTH Adrenal cortex Cortisol Alters glucose, Suppresses fat, and protein inflammatory and metabolism immune responses

Increases blood glucose Cortisol Release Increases blood glucose Stronger sympathetic system effect on heart rate Decreases nonessential energy-using activities like: Hormone production Metabolic rate and reproductive functions decrease Bone formation Red and white blood cell production Immune system becomes depressed

Question Why does cortisol production result in increased blood glucose levels? Glucose leads to a strong sympathetic nervous system response. Glucose stimulates RBC production. Glucose stimulates release of adrenaline. Glucose provides energy.

Answer Glucose provides energy. The body’s energy requirements increase during periods of stress. Cortisol is the “stress hormone” – one of the effects of cortisol release is increased blood glucose levels. Glucose helps to meet the body’s increased demand for energy.

Antidiuretic Hormone (ADH) Also called vasopressin Causes vasoconstriction Makes kidneys reabsorb water from urine to blood

Sympathetic System “Fight-or-Flight” Response Rapid response to trauma and emergency Epinephrine (adrenalin) and norepinephrine (noradrenalin) both released Both attach to adrenergic receptors on cells Pain, fear, low BP hypothalamus SNS activated SNS neurons Norepinephrine adrenal medulla Epinephrine released into blood

Sympathetic System “Fight-or-Flight” Response Blood pressure increased Blood flow to skin, guts, and kidneys reduced Skin becomes pale Urine production decreases GI activity decreases epinephrine and norepinephrine blood heart vessels increased HR vasoconstriction increased heart in skin, guts, strength kidneys increased BP

Renin-Angiotensin-Aldosterone Pathway Activated by: Sympathetic system Decreased blood flow to kidneys Angiotensin I: weak vasoconstriction Angiotensin-converting enzyme (ACE) Angiotensin II: stronger vasoconstriction Kidneys release renin Angiotensin I ACE Angiotensin II

Renin-Angiotensin-Aldosterone Pathway (cont.) Angiotensin II: stronger vasoconstriction Also stimulates the adrenal cortex Aldosterone released Angiotensin II adrenal cortex Aldosterone

Question True or False: Angiotensin-converting enzyme must be present in order for aldosterone to be released by the adrenal gland.

Answer True Without angiotensin-converting enzyme, angiotensin II would not be created. Angiotensin II stimulates the adrenal cortex to produce aldosterone.

Renin-Angiotensin-Aldosterone Pathway (cont.) Aldosterone released Na+/K+ ATPase in nephrons activated Kidneys reabsorb Na+ and water Kidneys secrete K+ aldosterone kidneys reabsorb Na+ secrete K+ and water increased blood volume oliguria = Very low urine output

stressors signs and change the internal symptoms environment of part of of the the body change general adaptation signs and response helps maintain symptoms of the normal function in spite general adaptation of the stressor response

Scenario: After an accident, a patient has the following: Increased heart rate No urine production No bowel sounds Pale, sweaty skin Low blood pressure Dilated pupils Elevated blood glucose Question: What should be fixed first? Why?

Stress “snowball” / positive feedback Central Nervous System which releases affect inflammatory hormones and mediators neurotransmitters which release affect immune cells

Effects of Stress on the Immune System Decreased immune cell production Decreased thymus activity Changes in the kind of immune cells produced

Question How does stress affect your immune system? The thymus atrophies. Fewer lymphocytes are produced. Inflammatory mediators are released. All of the above

Answer All of the above Stress causes the immune system to be suppressed. The thymus gland atrophies (shrinks), so that fewer T-lymphocytes are produced. Monocytes and lymphocytes cross the blood-brain barrier and release inflammatory mediators and cytokines.

Physiologic Stress Stress-induced changes in body functions Detected by body’s normal regulatory sensors The body alters function to restore normal balance When normal balance is restored, negative feedback stops the reaction

Psychosocial Stress Directly affects the central nervous system Turns on the stress responses, even when the body’s internal sensors have not detected an imbalance Question: Do the stress responses solve the person’s problem? Will negative feedback tell them when to turn off?

Acute Stress Question: Which organs of the body would you expect to see damaged by acute stress? Why?

Results of Long-Term Stress Chronic stress Sympathetic activity and cortisol are elevated Complications result from the reduced immune response Posttraumatic stress disorder Sympathetic system is activated Cortisol levels are decreased

Scenario: Mr. P saw violent combat in the army but he dealt with it and has become a successful air traffic controller. He is 50 and overweight: With increased blood pressure and occasional tachycardia Insomnia GI discomfort He has had several colds already this year, and wants a flu shot Question: What about his case might be stress-related?

Scenario (cont.): The doctor has recommended relaxation therapy Mr. P is furious about this “new age gobbledygook” Question: How will you explain its physiologic basis to him?